It has been known in the conveyor art to be careful and not extend the length of conveyor sections beyond the ability of the drive means to furnish power to the article supporting rollers. There has been used in various ways V-belts, flexible ropes, and similar drive means engaged with the underside of the rollers for the purpose of moving articles supported on the top of the rollers.
It is also known in the roller conveyor art that branch roller conveyors have been associated with a main roller conveyor, but in most instances the branch roller conveyors have required individual drive means, and great care must be exercised in order to properly synchronize the conveying rollers so that articles move as desired and without bumping into lead articles.
The prior art includes a billet conveyor associated with the heat treatment of certain materials, all as described by Cromwell U.S. Pat. No. 633,572 issued Sept. 26, 1899. In this prior art there has been disclosed the use of a single or double strand heat resistant wire rope trained over a system of horizontal and vertical positioned pulleys for traversing a main line of conveyance of the material to be heat treated, as well as directing the roller drive into branches so that the billets to be conveyed can be moved out of the main line and into the branches by the use of a switching member adapted to deflect the billets from the main line into the branches.
It has been known from the disclosure in Collins et al U.S. Pat. No. 3,219,166 issued Nov. 23, 1965 that the use of tapered article supporting rollers can be employed between main and branch lines to steer articles into the branch lines by elevating the tapered rollers so as to change the direction of movement of the articles. Such an arrangement of tapered rollers is also known from the disclosure in Reed et al U.S. Pat. No. 3,334,723 issued Aug. 8, 1967. In connection with flexible drive means for roller conveyors it is known from Werntz U.S. Pat. No. 4,117,923 of Oct. 3, 1978 to provide drive means in the form of a drum and accessory elements which power the flexible drive means and maintain a desired degree of slack take up so as to maintain an efficient transfer of power into the flexible drive means.